Manually-operable hydraulic stabilizing system

ABSTRACT

A stabilizing system includes a plurality of jacks, each operated by a corresponding hydraulic actuator. A hydraulic fluid transfer pump supplies hydraulic fluid to and receives hydraulic fluid from one or more pressure chambers of the actuator. A pilot-operated check or directional valve may be provided in fluid communication with one or more of the pressure chambers and configured to regulate the flow of hydraulic fluid to and from the pressure chamber. A directional control valve may connect the pump output with the jacks via respective pilot-operated directional valves. The directional control valve may include a plurality of switch positions respectively connecting the pump output with pairs of the jacks.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 16/196,949, filed Nov. 20, 2018, pending, which is acontinuation-in-part of U.S. patent application Ser. No. 15/912,030,filed Mar. 5, 2018, which claims the benefit of U.S. Provisional PatentApplication No. 62/513,766, filed Jun. 1, 2017, and U.S. ProvisionalPatent Application No. 62/478,271, filed Mar. 29, 2017, the entirecontents of each of which are hereby incorporated by reference in thisapplication.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

(NOT APPLICABLE)

BACKGROUND AND SUMMARY

A recreational vehicle (RV) or trailer tends to rock on its suspensionwhen persons move around inside the vehicle. It is known to provide sucha vehicle with a stabilizing system to mitigate this tendency.

A typical stabilizing system may include four independent stabilizingjacks, each located at or near one of the four corners of the vehicle,namely, the left front, right front, left rear, and right rear corners.Each such stabilizing jack typically includes a base mounted to thevehicle and a foot extendable and retractable from the base. The footmay be extended to a deployed position in which the foot is engaged withthe ground on which the vehicle is situated, and it may be retracted toa retracted (or travel) position in which the foot is sufficientlydistanced from the ground to allow the vehicle to be readily towed ordriven. Typically, each of the stabilizing jacks is independently andmanually operated. As such, in order to deploy the stabilization system,a user must go to each of the four corners of the vehicle and manuallydeploy the jacks one at a time. This can be time-consuming andinconvenient, particularly in the dark and/or in inclement weather.

Also, known stabilizing systems tend to load the vehicle's frameunevenly and cause it to twist. Such twisting can place undesirablestresses on the vehicle's body, resulting in leaks and damage to bodypanels and seams.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a hydraulically-operated stabilizingjack according to the present disclosure;

FIG. 2 is an end elevation view of the stabilizing jack of FIG. 1;

FIG. 3 is a cross-sectional side view of the jack of FIG. 1;

FIG. 4 is a hydraulic schematic diagram of a hydraulic stabilizingsystem configured to operate a plurality of hydraulically-operatedstabilizing jacks according to the present disclosure;

FIG. 5A is a perspective partial phantom view of a fluid transfer pumpaccording to the present disclosure;

FIG. 5B is a perspective view of a fluid transfer pump according to thepresent disclosure;

FIG. 5C is a side cross sectional view of a fluid transfer pumpaccording to the present disclosure;

FIG. 6 is a cross-sectional side view of another hydraulically-operatedstabilizing jack according to the present disclosure;

FIG. 7 is a hydraulic schematic diagram of another hydraulic stabilizingsystem configured to operate a plurality of hydraulically-operatedstabilizing jacks according to the present disclosure;

FIG. 8A is a cross-sectional view of an illustrative pilot-operateddirectional valve as may be used in the system of FIG. 7;

FIG. 8B is another cross-sectional view of an illustrativepilot-operated directional valve as may be used in the system of FIG. 7;

FIG. 9 is a hydraulic schematic diagram of a further illustrativehydraulic stabilizing system configured to operate a plurality ofhydraulically-operated stabilizing jacks according to the presentdisclosure;

FIG. 10 is a hydraulic schematic diagram of yet another illustrativehydraulic stabilizing system configured to operate a plurality ofhydraulically-operated stabilizing jacks according to the presentdisclosure; and

FIG. 11 is a hydraulic schematic diagram of an illustrative hydraulicstabilizing system incorporating a directional control valve to effectoperation of the jacks in pairs.

DETAILED DESCRIPTION

FIGS. 1-5 show an illustrative hydraulically-operated stabilizing system10 or parts thereof according to the present disclosure. As shown, thesystem includes four stabilizing jacks 12 that may be installed on anRV, trailer, or other vehicle. (The jacks 12 may be referred to hereinindividually as the first through fourth jacks 12A-12D or the jacks 12 nand collectively as the jacks 12 n. Similarly, the various components ofthe jacks 12 n may be referred to herein individually or collectively byappending their respective reference characters in a similar manner.) Inother embodiments, the system 10 may include more or fewer than fourjacks 12 n.

As best shown in FIGS. 1-3, each jack 12 n includes a base 14 configuredfor attachment to another structure, for example, an RV, a trailer, oranother vehicle. The interior of the base 14 defines a channel 16carrying a trunnion 18. A linear hydraulic actuator 20 is connected tothe base 14. As will be discussed further below, the actuator 20 isoperably connected to the trunnion 18 and is configured to selectivelydisplace the trunnion within the channel 16. The trunnion 18 may beconfigured, for example, to slide within the channel 16. In anembodiment, the trunnion 18 may include wheels configured to roll withinthe channel 16. Each jack 12 n also includes a strut (or struts) 22pivotally connected to the base 14, and a leg 24 having a first end anda second end. The first end of the leg 24 is operably connected to thetrunnion 18. The second end of the leg 24 may be connected to a foot 26,pivotally (as shown) or otherwise. The strut 22 is pivotally connectedto the leg 24 between the first end and the second end of the leg.

As best shown in FIG. 4, the actuator 20 includes an actuator cylinder28 having a first end and a second end, an actuator piston 30 slidablyengaged within the actuator cylinder, and an actuator piston rod 32connected to the actuator piston.

The actuator piston rod 32 is extendable and retractable with respect tothe actuator cylinder 28 through an end cap of the actuator cylinder inresponse to displacement of the actuator piston 30 within the actuatorcylinder. One skilled in the art would recognize that extension of theactuator piston rod 32 from the actuator cylinder 28 would cause the leg24 to articulate so that the second end of the leg (and the foot 26connected thereto) extends from the base 14, and that retraction of theactuator piston rod into the actuator cylinder would cause the leg toarticulate so that the second end of the leg (and the foot connectedthereto) retracts toward the base.

The actuator cylinder 28 and the actuator piston 30 cooperate to definean actuator first chamber 38 (which may sometimes be referred to hereinas the actuator extend chamber or the non-rod side of the actuatorpiston) and an actuator second chamber 40 (which may sometimes bereferred to herein as the actuator retract chamber or the rod side ofthe actuator piston).

A pilot-operated check valve 42 having first and second flow ports isconnected to the actuator retract chamber 40 with the flow ports influid communication therewith. The pilot-operated check valve 42 furtherhas a pilot port in fluid communication with a corresponding hydraulicextend line, as will be discussed further below.

The actuator extend chamber 38 has a maximum volume defined by theinterior of the actuator cylinder 28 and the free surface of theactuator piston 30 when the actuator piston rod 32 is fully extendedfrom the actuator cylinder (or when the actuator piston is fullydisplaced toward the second end of the actuator cylinder). The actuatorretract chamber 40 has a maximum volume defined by the interior of theactuator cylinder 28, the surface of the actuator piston 30 to which theactuator piston rod 32 is attached, and the actuator piston rod when theactuator piston rod is fully retracted into the actuator cylinder (orwhen the actuator piston is fully displaced toward the first end of theactuator cylinder). An actuator volume ratio (or actuator rod headratio) may be defined by the maximum actuator retract chamber volumedivided by the maximum actuator extend chamber volume.

The system 10 includes a fluid transfer pump 44 configured toselectively provide hydraulic fluid to, and selectively receivehydraulic fluid from the actuator extend chamber 38 and the actuatorretract chamber 40. As best shown in FIGS. 5A-5C, the pump 44 includes apump hydraulic cylinder 46 having a first end and a second end, a pumppiston 48 slidably engaged within the pump cylinder, and a pump pistonrod 50 connected to the pump piston. The pump cylinder 46 and the pumppiston 48 cooperate to define a pump first chamber 52 (which maysometimes be referred to herein as the pump extend chamber or thenon-rod side of the pump piston) and an actuator second chamber 54(which may sometimes be referred to herein as the pump retract chamberor the rod side of the pump piston).

The pump piston rod 50 is connected to and extends from one side (therod side) of the pump piston 48 and through an end cap of the pumpcylinder 46. The pump piston rod 50 is connected to the pump piston 48in a fluid-tight manner, for example, by a continuous weld. The pumppiston rod 50 is extendable and retractable with respect to the pumpcylinder 46 through an end cap of the pump cylinder in response todisplacement of the pump piston 48 within the pump cylinder. In anembodiment, the pump piston rod 50 may be omitted. In anotherembodiment, the fluid transfer pump 44 may be, for example, any othersuitable form of positive displacement pump.

The pump piston 48 defines a hole 56 extending axially therethrough andcoaxial with the pump piston rod 50. The hole 56 in the pump piston 48is internally threaded and configured for threaded engagement with adrive screw 60. The drive screw 60 is externally threaded and configuredfor threaded engagement with the internal threads of the hole 56. Thepump piston rod 50 defines a blind hole 58 extending partially andaxially therethrough from the end thereof coextensive with the pumppiston 48. The blind hole 58 in the pump piston rod 50 communicates withthe hole 56 in the pump piston 48 and with the pump extend chamber 52.The clearance between the threads of the drive screw 60 and those of thehole 56 in the pump piston 48 is sufficient to permit passage ofhydraulic fluid therebetween and to thereby preclude hydraulic lockingof the drive screw 60 with respect to the pump piston rod 50. As shown,the free end of the drive screw 60 is embodied as (or fitted with) adrive head 61, for example, a hex head, for engagement with an operator,for example, a hand tool or a power tool having a complementary head. Inan embodiment, the free end of the drive screw 60 or the drive head 61could be connected to a bi-directional electric motor (not shown).

As shown in FIG. 5A, the pump cylinder 46 and the pump piston 48 mayhave an oval or other non-round cross-section so that the pump piston iskeyed to the pump cylinder in non-rotational engagement. Alternatively,as shown in FIG. 5B the pump cylinder 46 and the pump piston 48 couldhave a round cross-section, and the pump piston rod 50 and thecomplementary opening in the end cap of the pump cylinder 46 could havecomplementary shapes. In other embodiments, the pump cylinder 46 and thepump piston 48 could be keyed together in other ways.

A pump extend chamber fill/bleed port 62 penetrates the pump cylinder 46to allow selective fluid communication between the pump extend chamber52 and the environment (which environment may include a receptacle forreceiving hydraulic fluid bled from the pump extend chamber bleed port).A pump retract chamber bleed port 64 penetrates the pump cylinder 46 toallow selective fluid communication between the pump retract chamber 54and the environment.

The pump extend chamber 52 has a maximum volume defined by the interiorof the pump cylinder 46 and the free surface of the pump piston 48 whenthe pump piston rod 50 is fully extended from the pump cylinder (thatis, when the pump piston is fully displaced toward the second end of thepump cylinder). The pump retract chamber 44 has a maximum volume definedby the interior of the pump cylinder 46, the surface of the pump piston48 to which the pump piston rod 50 is attached, and the pump piston rodwhen the pump piston rod is fully retracted into the pump cylinder (thatis, when the pump piston is fully displaced toward the first end of thepump cylinder). A pump volume ratio (or pump rod head ratio) may bedefined by the maximum pump retract chamber 54 volume divided by themaximum pump extend chamber 52 volume.

In an embodiment, the pump volume ratio is substantially similar to theactuator volume ratio of the actuators 20 of all of the jacks 12 ncollectively. More specifically, the pump extend chamber 52 volume maybe substantially similar to the sum of the actuator extend chamber 38volumes of the individual jacks 12 n, and the pump retract chamber 54volume may be substantially similar to the sum of the actuator retractchamber 40 volumes of the individual jacks 12 n. In an embodimentwherein the actuators 20 of all of the individual jacks 12 n areidentical, the pump volume ratio is substantially similar to the jackvolume ratio of the individual actuators 20 of the jacks 12 n.

In another embodiment, the pump volume ratio may be greater than thejack volume ratio of the actuators 20 of the jack 12 n collectively. Insuch an embodiment, the pump retract chamber 54 volume would be greaterthan the sum of the actuator retract chamber 40 volumes of the actuators20 of the individual jacks 12 n, and the pump extend chamber 52 volumeof the pump would be lesser than the sum of the actuator extend chamber38 volumes of the actuators of the individual jacks. In such anembodiment, over-retraction of the pump piston rod 50 could result invacuum being drawn in the pump retract chamber 54, thus causing thehydraulic fluid therein and/or in the corresponding actuator retractchambers 40 (and/or in the corresponding retract lines connecting thepump retract chamber with the actuator retract chambers, as will bediscussed below) to displace entrained air or “boil.” Also in such anembodiment, even full extension of the pump piston rod 50 may fail totransfer sufficient hydraulic fluid from the pump extend chamber 52 tothe actuator extend chambers 38 of the actuators 20 of all of the jacks12 n to fully extend the actuator piston rods 32 thereof.

In a further embodiment, the pump volume ratio may be lesser than thejack volume ratio of the actuators 20 of the jacks 12 n collectively. Insuch an embodiment, the pump extend chamber 52 volume would be greaterthan the sum of the actuator extend chamber 38 volumes of the actuators20 of the individual jacks 12 n, and the pump retract chamber 54 volumewould be lesser than the sum of the actuator retract chamber 40 volumesof the actuators 20 of the individual jacks. In such an embodiment, thepump extend chamber 52 may contain a substantial amount of surplushydraulic fluid, even when the actuator extend chambers 38 of theactuators 20 of all of the jacks 12 n are completely filled withhydraulic fluid. As such, continued operation of the pump in the extenddirection may over pressurize and cause failure of extend hydrauliclines connecting the pump extend chamber 52 with the actuator extendchambers 38 or other intervening components. Also, even full extensionof the pump piston rod 50 may fail to transfer sufficient hydraulicfluid from the extend chambers 38 of the actuators 20 of all of thejacks 12 n to the extend chamber of the pump to fully retract the pumppiston rods 24.

As shown in FIG. 4, the system 10 may be configured so that theactuators 20 of the first and second jacks 12A, 12B are controlled by afirst hydraulic circuit, and so that actuators of the third and fourthjacks 12C, 12D are controlled by a second hydraulic circuit.

The first hydraulic circuit includes a first hydraulic circuit extendline 66 connecting the pump extend chamber 52 with the respective extendchambers 38 of the actuators 20 of the first and second jack actuators12A, 12B, with the respective pilot ports of the pilot-operated checkvalves 42 of the first and second jack actuators, and with a firstextend line bleed port 68 in fluid communication. The first extend linebleed port 68 may be opened and closed using a removable cap or a bleedvalve to facilitate filling and bleeding of the first hydraulic circuit.As shown in FIG. 4, the first hydraulic circuit extend line 66 may beprovided in segments, with a first segment 66A connecting the pumpextend chamber 52 with the extend chamber 38 of the actuator 20 of thesecond jack actuator 12B, a second segment 66B connecting the extendchamber 38 of the actuator 20 of the second jack 12B with the extendchamber 38 of the actuator 20 of the first jack 12A and with the pilotport of the pilot-operated check valve 42 of the actuator 20 of thesecond jack 12B, and a third segment 66C connecting the extend chamber38 of the actuator 20 of the first jack 12A with the pilot port of thepilot-operated check valve 42 of the first jack 12A and also with thefirst extend line bleed port 68. In other embodiments, the firsthydraulic circuit extend line 66 may interconnect the foregoingcomponents in any suitable manner.

The first hydraulic circuit also includes a first hydraulic retract line70 connecting the pump retract chamber 54 with respective flow ports ofthe pilot-operated check valves 42 of the first and second jackactuators 12A, 12B and with a first retract line bleed port 72 in fluidcommunication.

The second hydraulic circuit includes analogous second hydraulic circuitextend and second hydraulic circuit retract lines hydraulically couplingthe pump 44 with the actuators 20 of the third and fourth jacks 12C, 12Din an analogous manner. In the drawings, such analogous extend andretract lines and other analogous hydraulic system components areidentified using primed reference characters corresponding to those usedabove in connection with the first hydraulic circuit.

In use, rotation of the drive screw 60 in a first direction causes thepump piston 48 to be displaced so as to force hydraulic fluid from thepump extend chamber 52 into the first and second hydraulic circuitextend lines and the extend chamber 38 of each of the actuators 20 n.Initially, the fluid pressure in the extend portion of the system(including the pump and actuator extend chambers and the correspondingextend lines) may be below the set point pressure of the pilot-operatedcheck valve 42 of any or all of the actuators 20 n. If so, therespective pilot-operated check valve 42 n checks flow out of therespective actuator retract chamber 40 n, thereby precludingdisplacement of the respective actuator piston 30 n.

With the pilot-operated check valve 42 of any of the actuators 20 inthis state, hydraulic fluid cannot appreciably flow between the pump 44and the respective actuator 20. Continued rotation of the drive screw 60eventually causes the fluid pressure in the corresponding extend linesto rise to and above the set point pressure of the respectivepilot-operated check valve 42, thus unseating the pilot-operated checkvalve plug or disc and thereby allowing displacement of the respectiveactuator piston 30 and flow of hydraulic fluid out of the respectiveactuator retract chamber 40, through the corresponding retract line, andinto the pump retract chamber 54. Consequently, hydraulic fluid isreceived in the actuator extend chamber 38 from the pump extend chamber52, and the actuator piston rod 32 extends from the respective actuatorcylinder 28, thereby retracting the leg 24 of the jack 12 toward thebase 14 of the jack. When the drive screw 60 stops rotating, thepressure in the extend lines falls below the pilot-operated check valve42 setpoint pressure and the pilot-operated check valve plug or discengages with its seats, thereby checking further discharge of hydraulicfluid from the actuator retract chamber 40.

During the foregoing extend operation, the actuator piston 28 of one ofthe first and second jacks 12A, 12B may bottom out in the respectiveactuator cylinder 28 before the actuator piston of the other of thefirst and second jacks bottoms out in the respective actuator cylinder.Because the extend chambers 38 of the first and second actuators 20A,20B are connected together in fluid communication, the actuator piston30 of the other of the first and second jack actuators can continue toextend until it, too, bottoms out.

Rotation of the drive screw 60 in a second direction causes the pumppiston 48 to be displaced so as to force fluid out of the pump retractchamber 54 into the corresponding retract lines and into the actuatorretract chambers 40 of each of the actuators 20. Consequently, theactuator piston 30 is displaced so as to force hydraulic fluid out ofthe actuator extend chamber 40, and the actuator piston rod 32 retractsinto the respective actuator cylinder 28, thereby extending the leg 24of the jack 12 away from the base 14 of the jack. When the drive screw60 stops rotating, the plugs of the pilot-operated check valves 42engage with their seats and check discharge of hydraulic fluid from thejack retract chambers 40.

During the foregoing retract operation, the leg 24 of one of the firstand second jacks 12A, 12B may bear against the ground before the leg ofthe other of the first and second jacks bears against the ground.Because the retract chambers 40 of the first and second actuators 20A,20B are connected together in fluid communication, the leg 24 of theother of the first and second jack actuators 12A, 12B can continue toextend until it, too, bears against the ground. When the legs 24 of boththe first and second jacks 12A, 12B have come into bearing against theground, further displacement of the corresponding actuator pistons 30 isinhibited. Once displacement of the actuator piston 30 has halted, flowof hydraulic fluid from the pump extend chamber 52 to the actuatorextend chamber 38 is halted, and the plug or disc of the pilot-operatedcheck valve 42 is seated. (Displacement of the actuator piston 30 may behalted by ceasing rotation of the drive screw 60, because the respectiveactuator pistons have bottomed out in the actuator cylinder 28, and/orbecause the respective jack legs 24 have bottomed out against theground.

The third and fourth actuators 20C, 20D behave in a manner similar tothe first and second actuators 20A, 20B.

FIGS. 6-8 show another illustrative hydraulic stabilizing system 110according to the present disclosure. As shown, the system includes fourstabilizing jacks 112 that may be installed on an RV, trailer, or othervehicle. (The jacks 112 may be referred to herein individually as thefirst through fourth jacks 112A-112D or the jacks 112 n and collectivelyas the jacks 112 n. Similarly, the various components of the jacks 112 nmay be referred to herein individually or collectively by appendingtheir respective reference characters in a similar manner.) In otherembodiments, the system 110 may include more or fewer than four jacks112 n.

FIG. 6 shows an illustrative jack 112. The jack 112 is in most respectsidentical or analogous to the jack 12 described above. The components ofthe jack 112 that have identical or analogous counterparts in the jack12 may be identified herein by like reference numbers, incremented by100, and generally will not be discussed further. As such, the followingdiscussion of the jack 112 generally is directed to differences betweenthe jack 112 and the jack 12.

As shown in FIG. 6, the jack 112 may further include a biasing element113 configured to bias the leg 122 of the jack to a retracted position.The biasing member 113 may be embodied as a helical tension springconnected between the base 114 and the trunnion 116 of the jack 112. Inother embodiments, the biasing element 113 may be embodied in otherways.

Also, as best shown in FIG. 7, the actuator 120 of the jack 112 differsin some regards from the actuator 20 of the jack 12. The components ofthe actuator 120 that have identical or analogous counterparts in theactuator 20 may be identified herein by like reference numbers,incremented by 100, and generally will not be discussed further. Assuch, the following discussion of the actuator 120 generally is directedto differences between the actuator 120 and the actuator 20.

The non-rod side 138 of the actuator 120 need not be plumbed to receiveor reject hydraulic fluid as is the non-rod side 38 of the actuator 20.Instead, the non-rod side 138 of the actuator 120 includes a biasingelement 178, for example, a coil compression spring, acting against thenon-rod side end of the actuator cylinder 128 and the non-rod side ofthe actuator piston 130. As such, the biasing element 178 biases theactuator piston 130 toward the rod-side end of the actuator cylinder. Inan embodiment, the biasing element 178 could be compressed gas, forexample, compressed air, sealed within the actuator extend chamber 138,or within a sealed container (not shown) disposed within the actuatorextend chamber.

The actuator 120 does not include a pilot-operated check valve as doesthe actuator 20. Instead, the actuator 120 includes a pilot-operateddirectional valve 176. FIGS. 8A and 8B show an illustrativepilot-operated directional valve 176 including a first flow port 180connected to the retract line 170 and a second flow port 182 connectedto the corresponding actuator retract chamber 140. Due to the springbias via biasing element 178, which as noted could be a spring orcompressed gas or the like, it is not necessary to connect a return lineto the actuator extend chamber 138. The valve 176 also includes a ballor plug 184 selectively engageable with a valve seat 186. The plug 184may be selectively mechanically displaced off the valve seat 186 by anoperator including a rod 188 connected to an operator piston 190slidingly received within a bore 192 in the body of the valve 176. AnO-ring 194 may be provided in connection with the piston 190 and thebore to effect a fluid-tight seal therebetween. For example, the O-ring194 may be disposed in a groove defined by the outer circumference ofthe piston 190. A biasing spring 196 may be disposed between a face ofthe non-rod side of the piston 190 and a bearing surface 198.

As best shown in FIG. 8A, the biasing spring 196 is configured to biasthe piston 190 and the attached rod 188 toward a first position in whichthe rod precludes the plug 184 from engaging with the seat 186. As bestshown in FIG. 8B, the biasing force provided by the biasing spring 196may be overcome by sufficient fluid pressure (the pilot-operateddirectional control valve setpoint pressure) in the correspondingretract line 170 applied to the rod side of the piston 190 so as todisplace the piston and the rod 188 toward a second position in whichthe rod does not preclude the plug from engaging with the seat 186.

With the piston 190 in the first position and the plug 186 precludedfrom engagement with the seat 186, hydraulic fluid may flow between theretract line 170 and the actuator retract chamber 140 in bothdirections. With the piston 190 in the second position and the plug 186not precluded from engagement with the seat 186, hydraulic fluid mayflow from the retract line 170 to the actuator retract chamber 140, butnot in the opposite direction.

In use, rotation of the drive screw 160 in a first direction causes thepump piston 148 to be displaced so as to draw hydraulic fluid from theactuator retract chambers 140 of the jacks 112A-112D through thecorresponding retract lines 170 and into the pump retract chamber 154.If the fluid pressure in the retract line 170 initially is above thepilot-operated directional valve setpoint, the check valve piston 190and rod 188 of each of the jacks 112A-112D initially will be in thesecond position and the corresponding plugs 184 may be engaged with thecorresponding seats 186. The foregoing operation of the drive screw 152will reduce the fluid pressure in the retract lines 170 to a pressurebelow the setpoint pressure. Consequently, the biasing springs 196 willdisplace the pistons 190 and the rods 188 to the first position, therebydisengaging the plugs 184 from the seats 186 and enabling flow ofhydraulic fluid from the actuator retract chambers 140 of each of thejacks 112A-112D, through the retract lines 170, and into the pumpretract chamber 154. As the hydraulic fluid is withdrawn from theactuator retract chambers 140, the biasing elements 138 and the reducedpressure in the actuator retract chambers cooperate to extend theactuator piston rods 132 from the actuator cylinders 128 and, therefore,to retract the jack legs 122 toward the jack bases 114.

Operation of the drive screw 160 in a second direction causes the pumppiston 148 to be displaced so as to force hydraulic fluid out of thepump retract chamber 154, through the retract lines 170, and into theactuator retract chambers 140 of each of the jacks 112A-112D.Consequently, the actuator pistons 130 and pistons rods 132 areretracted into the corresponding actuator cylinders 128 and the jacklegs 122 are extended from the jack base 114. When the jack leg 122 ofone of the first jack 112A and the second jack 112B bottoms out againstthe ground, the corresponding actuator piston 130 and piston rod 132stop moving appreciably, but hydraulic fluid continues to be provided tothe actuator retract chamber of the other of the first jack and thesecond jack without an appreciable increase in hydraulic pressure in thecorresponding retract line 170. When the jack leg 122 of the other ofthe first jack 112A and the second jack 112B bottoms out against theground, its actuator piston 130 and piston rod 132 stop movingappreciably, and hydraulic pressure begins to build in the correspondingretract line 170. When the hydraulic pressure in the retract line 170rises above the pilot-operated directional control valve setpointpressure, the pistons 190 and piston rods 188 of the directional valves176 move to the second state, thus enabling the plugs 182 to engage withthe seats 184, thereby precluding back flow from the respective actuatorretract chambers to the retract line 170.

The third and fourth jacks 112C, 112D operate in a similar manner.

The pump 144 is similar to the pump 44 except that the non-rod side 152of the pump 144 is not plumbed to receive or reject hydraulic fluid 44(the non-rod side of the pump 144 may be referred to herein as the dryside or dry chamber, and the rod side of the pump 144 may be referred toherein as the fluid side or fluid chamber). In an embodiment, the dryand fluid chambers of the pump 144 could be reversed. That is, the fluidchamber of the pump 144 could be on the non-rod side of the pump piston148, and the dry chamber 142 could be on the rod side of the pumppiston.

FIG. 9 shows a further illustrative hydraulic stabilizing system 210according to the present disclosure. The system 210 is substantiallysimilar to the system 110 in most regards. Features of the system 210having direct counterparts in the system 110 are identified herein usinglike reference characters, incremented by 100. For example, the system210 as shown includes four stabilizing jacks 212 similar or identical tothe jacks 112 of the system 110.

The system 210 differs from the system 110 primarily in that the pump244 of the system 210 is embodied as a reciprocating hand pump, whereasthe pump 144 of the system 110 is embodied as a screw-operated pump.

The pump 244 includes a pump hydraulic cylinder 246 having a first endand a second end, a pump piston 248 slidably engaged within the pumpcylinder, and a pump piston rod 250 connected to the pump piston. Thepump cylinder 246 and the pump piston 248 cooperate to define a pumpfirst chamber 252 (which may sometimes be referred to herein as the pumpdry chamber or the rod side of the pump piston) and a pump secondchamber 254 (which may sometimes be referred to herein as the pump fluidchamber or the non-rod side of the pump piston). The pump piston rod 250is connected to and extends from one side (the rod side) of the pumppiston 248. The pump piston rod 250 is extendable and retractable withrespect to the pump cylinder 246 in response to displacement of areciprocating pump actuator 251.

The pump 244 also includes a fluid reservoir 245, a first check valve247 enabling selective fluid communication between the reservoir and thefluid chamber 254, a second check valve 249 enabling selective fluidcommunication between the fluid chamber and the retract chambers 240 ofthe actuators 212 n, and a fluid control valve 253 enabling selectivefluid communication between the retract chambers of the actuators andthe reservoir.

In operation, with the control valve 253 closed, a user may operate thepump 244 by operating the reciprocating actuator 251 to withdraw thepiston rod 250 from the cylinder 246, thereby moving the piston 248 soas to increase the volume of the fluid chamber 252, thereby decreasingthe pressure in the fluid chamber. The pressure reduction tends to closeor cause to remain closed the second check valve 249 to draw fluid fromthe reservoir 245 through the first check valve 247 into the fluidchamber 254. The user may further operate the reciprocating actuator 251to retract the piston rod 250 into the cylinder 246, thereby moving thepiston 248 so as to decrease the volume of the fluid chamber 254,thereby increasing the pressure in the fluid chamber. The pressureincrease tends to close or cause to remain closed the first check valve247 and to force fluid from the fluid chamber 254, through the secondcheck valve 249, and into the retract chambers 240 of the actuators. Theuser may continue to operate the reciprocating actuator 251 as may benecessary to achieve a desired state of retraction of the actuatorpistons 230 and actuator piston rods 232 into the actuator cylinders228.

The user may open the control valve 253 to relive fluid from the retractchambers 240 of the actuators 212 n to the reservoir 245.

FIG. 10 shows yet another illustrative hydraulic stabilizing system 310according to the present disclosure. The system 310 is substantiallysimilar to the system 210 in most regards. Features of the system 310having direct counterparts in the system 210 are identified herein usinglike reference characters, incremented by 100. For example, the system310 as shown includes four stabilizing jacks 312 similar or identical tothe jacks 212 of the system 210.

The system 310 differs from the system 210 primarily in that the system310 includes a pump system 360 including both a reciprocating hand pump344 and a gear pump 362 (or other rotary positive displacement pump)connected in parallel between the reservoir 345 and the retract chambers340 of the actuators 312 n.

The hand pump 344 of the system 310 differs from the hand pump 244 ofthe system 210 in that the hand pump 344 is double acting. That is, thepump first chamber 352 of the pump 344 also is a fluid chamberconfigured to selectively draw hydraulic fluid from the reservoir 345and discharge the hydraulic fluid to the retract chambers 340 of theactuators 312 n. As such, the pump 344 also includes a third check valve357 enabling selective fluid communication between the reservoir 345 andthe pump first chamber 352 and a third check valve 359 enablingselective fluid communication between the pump first chamber and theretract chambers 340 of the actuators 312 n.

The gear pump 362 may include a pump shaft (not shown) and a drive head(not shown) connected to the pump shaft. The drive head may be engagedby a tool having a complementary drive head configured to turn the pumpshaft. The tool may be a hand crank, a power tool, for example, anelectric drill, or a dedicated and permanently or semi-permanentlyinstalled motor.

The system 310 also includes a fifth check valve 364 connected betweenthe gear pump 344 and the retract chambers 340 of the actuators 312 n topreclude backflow of hydraulic fluid through the gear pump 362.

The system further includes a pressure relief valve 366 connectedbetween the retract line 370 and the reservoir 345. The pressure reliefvalve 366 is configured to relieve hydraulic fluid from the retract line370 to the reservoir 345 in the event the fluid pressure exceeds thepressure relief valve setpoint.

The system 310 may be operated in a manner similar to the system 310.The gear pump 362 may be used in lieu of the hand pump 344 to rapidlydeploy the jacks 212 n. The hand pump 344 may be better suited formaking fine adjustments to the state of deployment of the jacks 212 n.

In the embodiments illustrated and described herein, extension of theactuator piston rod 32, 132, 232, 332 causes the leg 24, 124, 224, 324of the jack 12, 112, 212, 312 to retract, and retraction of the actuatorpiston rod causes the leg of the jack to extend. In other embodiments,this relationship could be reversed. For example, the actuator 20, 120,220, 320 could be mounted to the base 14, 114, 214, 314 of the jacks 12,112, 212, 312 so as to act on the opposite side of the trunnions 18,118, 218, 318.

In such a reversed embodiment, the flow ports of the pilot-operatedcheck valves 42 of the jack actuators 12 n would be connected to theextend chambers 38 of the jack actuators and the corresponding extendlines, and the pilot ports of the pilot-operated check valves would beconnected to the retract lines 70 in a reversal of the arrangement shownand described above.

Also, in such a reversed embodiment, the hydraulic pump 144, 244 or pumpsystem 360 would communicate hydraulic fluid with the actuator extendchambers 138, 238, 338 instead of with the actuator retract chambers.Further, the flow ports of the pilot-operated directional valves 176,276, 376 of the actuators 120 n, 220 n, 320 n would be connected to theactuator extend chambers 138, 238, 338 and to corresponding extendlines, and the pilot ports of the pilot-operated directional checkvalves would be connected to the extend lines in a reversal of thearrangement shown and described above.

An exemplary reversed embodiment is shown in FIG. 11. FIG. 11 shows afurther illustrative hydraulic stabilizing system 410 according to thepresent disclosure. The system 410 is substantially similar to thesystem 310 in most regards, without the gear pump 362. Features of thesystem 410 having direct counterparts in the system 310 are identifiedherein using like reference characters, incremented by 100. For example,the system 410 as shown includes four stabilizing jacks 412 similar oridentical to the jacks 312 of the system 310.

As noted, the actuator versus jack direction is reversed—i.e., pumpoutput is directed to the extend chambers of the jacks 412. Thisconfiguration is exemplary, and the system could alternatively utilize ac-jack style design like that of the previously-described embodiments.

Aside from the gear pump 362, the system 410 differs from the system 310primarily in the addition of a directional control valve 480. Thedirectional control valve 480 includes a user-operated actuator 482 tocontrol valve position. In a first or all jacks position 483, theactuator 482 connects the pump 444 to all four (or more) of the jacks412A-412D. In this configuration, fluid from the pump 444 is directed inparallel to all of the jacks 412A-D. This operation is similar to thepreviously-described embodiments. In a second or front jacks position484, the actuator 482 connects the pump 444 to the front jacks 412A,412B only; in a third or rear jacks position 485, the actuator connectsthe pump 444 to the rear jacks 412C, 412D only; in a fourth or leftjacks position 486, the actuator connects the pump 444 to the left jacks412A, 412C only; and in a fifth or right jacks position 487, theactuator connects the pump 444 to the right jacks 412B, 412D only. Byselectively controlling the jacks 412 in pairs, the operator can moreefficiently level the vehicle. For example, by controlling the jacks 412in pairs, the user cannot twist the chassis despite it having noelectronic system to monitor. The paired system forces the user to liftan entire “side” of the coach.

In the previous embodiments, the system captured gas on the retract sideof the cylinders to act as a spring return for the jacks. A similarfunction may be achieved using a separate accumulator 488 to handle thevolume. The separate accumulator 488 accommodates different sizerequirements.

The FIG. 11 system utilizes isolated check valves or pilot-operateddirectional valves 476 that are interposed between the directionalcontrol valve 480 and the jacks 412. The valves 476 may be attached tothe directional control valve 480 or to the jacks 412. The valves 476passively isolate the jacks without the user having to manually engageblocking valves or purchase more expensive solenoid operated valves.

In other embodiments, the actuators 20 n, 120 n, 220 n, 320 n, 420 nthemselves could function as the jacks. More specifically, each of theactuators 20 n, 120 n, 220 n could be mounted to the vehicle with therespective actuator cylinder 28, 128, 228, actuator piston 30, 130, 230,and actuator piston rod 32, 132, 232 oriented vertically. A foot (notshown) could be attached to the free end of the actuator piston rod 30,132, 232, 332. In such embodiments, the flow ports of the pilot-operatedvalves 26, 176, 276 of the actuators 20 n, 120 n, 220 n, 320 n would beconnected to the actuator extend chambers 38, 138, 238, 338 and to thecorresponding extend lines, and the pilot ports of the pilot-operatedcheck valves 26 (in embodiments using them) would be connected to theretract lines in a reversal of the arrangement shown and describedabove.

The illustrated embodiments of the systems 10, 110, 210, 310, 410include four stabilizing jacks 12 n, 112 n, 212 n, 312 n, 412 n. Otherembodiments could include more or fewer than four stabilizing jacks 12n, 112 n, 212 n, 312 n, 412 n. Also, the illustrated embodiments of thesystems 10, 110 include two hydraulic circuits. Other embodiments couldinclude more or fewer than two hydraulic circuits. Further, theillustrated embodiments of the systems 210, 310, 410 include onehydraulic circuit. Other embodiments could include two or more hydrauliccircuits.

In any of the foregoing embodiments, the hydraulic circuit is configuredto allow equalization of pressure at each of the actuators 20 n, 120 n,220 n, 320 n, 420 n. This feature may inhibit any single jack 12 n, 112n, 212 n, 312 n, 412 n from taking on a disproportionate load that couldcause the vehicle's frame to twist.

A pump system similar to the pump system 360 of the system 310 may beprovided in lieu of the pumps 44, 144, 244 of the systems 10, 110, 210.

A gear pump similar to the gear pump 360 of the system 310 may beprovided in lieu of the piston-type pumps 44, 144 of the systems 10,110. Such a gear pump used in the system 10 would be bi-directional.

A pressure relief valve similar to the pressure relief valve 366 of thesystem 310 may be provided in connection with the pumps 44, 144, 244 ofthe systems 10, 110, 210.

Terms of orientation, for example, upper, lower, vertical horizontal,and the like as may be used herein should be construed to refer torelative rather than absolute orientation unless context clearlydictates otherwise.

The embodiments shown and describe herein are illustrative and notlimiting. Features described in connection with a given embodiment maybe included in other embodiments to the greatest extent possible. Forexample, without limitation, pilot-operated check valves could beprovided as substitutes for the pilot-operated directional valves of thesystems 110, 210, 310, 410, and pilot-operated directional valves couldbe provided as substitutes for the pilot-operated check valves of thesystem 10. As another non-limiting example, a single-actingreciprocating pump could be provided as a substitute for thedouble-acting reciprocating pump of the system 310, and a double-actingreciprocating pump could be provided as a substitute for thesingle-acting reciprocating pump of the system 210.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A hydraulic stabilizing system comprising: a plurality of hydraulicstabilizing jacks, each of said jacks having an actuator comprising: anactuator cylinder; an actuator piston slidingly engaged with saidactuator cylinder, said actuator piston cooperating with said actuatorcylinder to define an actuator extend chamber and an actuator retractchamber; an actuator piston rod connected to said actuator piston andselectively extendable from and retractable into said jack cylinder; andone of a pilot-operated check valve and a pilot-operated directionalvalve having a first flow port connected to said actuator retractchamber in fluid communication therewith; a fluid reservoir; a fluidtransfer pump having an input in fluid communication with said fluidreservoir, wherein said fluid transfer pump is one of a reciprocatingpump and a gear pump; a hydraulic line connecting an output of said pumpwith said one of said actuator retract chamber and said actuator extendchamber of at least one of said actuators and with a second flow port ofsaid one of pilot-operated check valve and a pilot-operated directionalvalve of said at least one of said actuators; and a control valveoperable to selectively establish fluid communication between said firsthydraulic line and said fluid reservoir.
 2. The system of claim 1further comprising a pressure relief valve configured to selectivelyrelieve fluid from said hydraulic line to said fluid reservoir.
 3. Thesystem of claim 1 wherein said fluid transfer pump is a gear pump. 4.The system of claim 1, wherein said fluid transfer pump is areciprocating pump comprising: a first fluid chamber having a firstinput in selective fluid communication with said fluid reservoir and afirst output in selective fluid communication with said hydraulic line;and a second fluid chamber having a second input in selective fluidcommunication with said fluid reservoir and a second output in selectivefluid communication with said hydraulic line.
 5. The system of claim 1wherein said one of said pilot-operated check valve and pilot operateddirectional valve is configured to selectively enable and disable flowbetween said output of said pump and said one of said actuator retractchamber and said actuator extend chamber of said at least one of saidactuators.
 6. The system of claim 1 further comprising a biasingmechanism associated with the other of said actuator retract chamber andsaid actuator extend chamber of said at least one of said actuators,said biasing mechanism configured to bias said actuator piston of saidat least one of said actuators from said one of said actuator retractchamber and said actuator extend chamber of said at least one of saidactuators toward the other of said actuator retract chamber and saidactuator extend chamber of said at least one of said actuators.
 7. Thesystem of claim 1 further comprising a biasing mechanism associated withthe other of said actuator retract chamber and said actuator extendchamber of said at least one of said actuators, said biasing mechanismconfigured to bias said actuator piston of said at least one of saidactuators from said other of said actuator retract chamber and saidactuator extend chamber of said at least one of said actuators towardsaid one of said actuator retract chamber and said actuator extendchamber of said at least one of said actuators.
 8. The system of claim 1installed on a vehicle.
 9. The system of claim 8, wherein said vehiclecomprises four corners and said plurality of jacks comprises four jacks,each of said four jacks located at a corresponding one of said fourcorners.
 10. The system of claim 9, further comprising a directionalcontrol valve connected to the hydraulic line and connecting the outputof said pump with one of said actuator retract chamber and said actuatorextend chamber of the plurality of said actuators via respectivepilot-operated directional valves of said plurality of said actuators,wherein said directional control valve includes a plurality of switchpositions respectively connecting the output of said pump with pairs ofsaid actuators.
 11. The system of claim 10, wherein said four jackscomprise a left front jack, a right front jack, a left rear jack, and aright rear jack, and wherein said plurality of switch positions includeat least one of (1) a front jacks positions connecting the output ofsaid pump with the left front jack and the right front jack, (2) a rearjacks position connecting the output of said pump with the left rearjack and the right rear jack, (3) a left jacks position connecting theoutput of said pump with the left front jack and the left rear jack, and(4) a right jacks position connecting the output of said pump with theright front jack and the right rear jack.
 12. A hydraulic stabilizingsystem comprising: a plurality of hydraulic stabilizing jacks, each ofsaid jacks having an actuator comprising: an actuator cylinder; anactuator piston slidingly engaged with said actuator cylinder, saidactuator piston cooperating with said actuator cylinder to define anactuator extend chamber and an actuator retract chamber; and an actuatorpiston rod connected to said actuator piston and selectively extendablefrom and retractable into said jack cylinder; a fluid transfer pump; ahydraulic line receiving output from said pump; and a directionalcontrol valve connected to the hydraulic line and connecting the outputof said pump with one of said actuator retract chamber and said actuatorextend chamber of the plurality of said actuators via respectivepilot-operated directional valves of said plurality of said actuators,wherein said directional control valve includes a plurality of switchpositions respectively connecting the output of said pump with pairs ofsaid actuators.
 13. The system of claim 12, comprising four of saidhydraulic stabilizing jacks including a left front jack, a right frontjack, a left rear jack, and a right rear jack, wherein said plurality ofswitch positions include (1) a front jacks positions connecting theoutput of said pump with the left front jack and the right front jack,(2) a rear jacks position connecting the output of said pump with theleft rear jack and the right rear jack, (3) a left jacks positionconnecting the output of said pump with the left front jack and the leftrear jack, and (4) a right jacks position connecting the output of saidpump with the right front jack and the right rear jack.
 14. The systemof claim 13, wherein said plurality of switch positions furthercomprises an all jacks position connecting the output of said pump withthe left front jack, the right front jack, the left rear jack, and theright rear jack.
 15. The system of claim 12, wherein the switchpositions of said directional control valve are selected via auser-operator actuator.
 16. A method of operating a hydraulicstabilizing system including at least four hydraulic stabilizing jacksbeing a left front jack, a right front jack, a left rear jack, and aright rear jack, the method comprising: (a) setting a position of adirectional control valve; (b) activating a fluid transfer pump; and (c)driving at least two of the at least four hydraulic stabilizing jacksvia output from the fluid transfer pump, wherein the directional controlvalve includes a plurality of switch positions respectively connectingthe fluid transfer pump with pairs of the hydraulic stabilizing jacks,and wherein step (c) is practiced by driving one of the pairs of thehydraulic stabilizing jacks according to the position of the directionalcontrol valve.
 17. A method according to claim 16, wherein step (a) ispracticed by setting the position of the directional control valve asone of (1) a front jacks positions connecting the output of the fluidtransfer pump with the left front jack and the right front jack, (2) arear jacks position connecting the output of the fluid transfer pumpwith the left rear jack and the right rear jack, (3) a left jacksposition connecting the output of the fluid transfer pump with the leftfront jack and the left rear jack, and (4) a right jacks positionconnecting the output of the fluid transfer pump with the right frontjack and the right rear jack.
 18. A method according to claim 17,wherein step (a) is practiced by setting the position of the directionalcontrol valve as (5) an all jacks position connecting the output of thefluid transfer pump with the left front jack, the right front jack, theleft rear jack, and the right rear jack.
 19. A method according to claim16, wherein step (c) is practiced by driving the hydraulic stabilizingjacks via respective pilot-operated directional valves interposedbetween the directional control valve and the hydraulic stabilizingjacks.